feat(scope): dsh-scope scoped-context registration primitive

createScope(ctx, key) mints a tagged context over a synchronously-usable
no-op-plugin fiber (one fact drives visibility AND lifetime); scopeOf reads
the tag through the prototype chain; scopeTarget(base, key) builds the
scope-filtered dispatch carrier over cordis Context.filter, composing the
base's own filter, branded Scoped<T> and runtime-marked for the dev
invariants. Scope.rawDispose exposes the exact cordis disposer so a
composite effect can nest the scope's teardown at its yield position.

docs/config-catalog.md

@@ -815,4 +815,5 @@ Imported as libraries by other packages; a `cordis.yml` cannot load them.
 - `@deepseek-ai/dsh-app-boot` ([`packages/ui/app-boot/src/index.ts`](../packages/ui/app-boot/src/index.ts))
 - `@deepseek-ai/dsh-brand` ([`packages/util/brand/src/index.ts`](../packages/util/brand/src/index.ts))
 - `@deepseek-ai/dsh-hook-protocol` ([`packages/hooks/hook-protocol/src/index.ts`](../packages/hooks/hook-protocol/src/index.ts))
+- `@deepseek-ai/dsh-scope` ([`packages/core/scope/src/index.ts`](../packages/core/scope/src/index.ts))
 - `@deepseek-ai/dsh-subagent-inprocess` ([`packages/subagent/subagent-inprocess/src/index.ts`](../packages/subagent/subagent-inprocess/src/index.ts))